* Low brake fluid: This is the most common cause. Check the brake fluid reservoir (usually a clear plastic container near the master cylinder under the hood). If it's low, you have a leak somewhere in the system. Do not drive the car until this is addressed. A leak could lead to complete brake failure.
* Brake wear: The brake pads or shoes might be worn down. This will trigger the light on some models when the pads are nearing the end of their life. You'll need to get them inspected and replaced if necessary.
* Brake system malfunction: This is the most serious possibility. The problem could be with the master cylinder, wheel cylinders, calipers, ABS system (if equipped), or a variety of other components. A leak, a failed sensor, or internal damage could be the cause.
What to do:
1. Do not drive the car extensively. Only drive it if absolutely necessary and only very short distances to a safe location.
2. Check the brake fluid level. This is the first and easiest thing to check. If it's low, do not drive the car until the leak is found and repaired.
3. Have the car inspected by a qualified mechanic immediately. They have the tools and expertise to diagnose the specific problem and make the necessary repairs. Ignoring the problem can lead to brake failure, which could cause an accident. They'll likely use a code reader (if your car has a diagnostic port) to determine what the sensor is reporting.
4. Never attempt to repair the brakes yourself unless you have extensive experience. Brake systems are complex, and improper repair could be very dangerous.
In short, a brake light is a serious warning. Get it checked by a professional as soon as possible to avoid a potentially dangerous situation.
